Weighing device

ABSTRACT

A weighing device for the determination of weight of a fiber material is provided. The weighing device includes multiple weighing arms. Each of the weighing arms is pivotably supported on one end. Also, each of the weighing arms is supported on an opposite end by a weighing element. The weighing arms are configured for supporting and transporting the fiber material. The weighing element provides a signal for the determination of weight of the fiber material.

BACKGROUND

The invention concerns a weighing device for the continuousdetermination of the weight per unit area of fiber material running as aband or as matting, which is delivered out of a preceding machine orfrom a fiber material container to the weighing device. The materialleaves the weighing device to enter a subsequent fiber working machineor fiber material storage facility.

Weighing apparatuses of this kind, as they, are known in the art, showgreat variation in design. The fiber material is conducted on anessentially horizontal transport belt, beneath which the weighingapparatus is placed. In EP 0 635 589 A1 an electronic belt weigher isdescribed, which precedes the intake apparatus of a carding machine orthe like. The fiber mat resulting therefrom is discharged onto anendless, running belt leading to the intake apparatus of the cardingmachine. In the midsection of this running belt, which carries the fibermat, is located a measurement device. This measurement device determinesthe weight of the fiber mat on a given weighing stretch. By use of a“set-point vs. actual” comparison, the belt speed, which is the matvelocity, is controlled so that added spinning material matches adesired weight per unit area or band weight of the finished product. Theset value for the surface or fiber band weight can relate itself to theoutput of one of successive fiber processing machines. One of thesemachines can be for instance, a matting band layering machine.

This type of band-weight determination is prone to error in that theloading of the weighing device under the transport belt is affected bythe elasticity and the tension of the belt as it transports the fiberband.

In order to avoid this fault and to render the weighing apparatusindependent of the feed and removal of the material to be weighed,patent number DE 39 13 733 A1 proposes to make the support belt with theweighing device independent from the feed table. The patent attempts todo this in such a manner that the support belt with its drive apparatusalong with the spinning goods carried thereon is weighed. Uponsubtraction of the tare, the weight of the spinning goods can bedetermined. Following the weighing belt, but independent thereof, is asubsequent feed table for the next machine.

Experience has shown that this arrangement is not satisfactory. Onereason is that upon the transport of fiber mass in the form of aprecompressed matting or band, bridge formations appear at thetransitions between the transport belt of the feed table and theweighing belt as well as at the subsequent transport belt. This bridgeformation has the effect of giving support to the fiber mass in thetransition zone at the neighboring transport element. The results of themeasurement are falsified in that the fiber mass which is on thetransport belt can support itself by its own fiber friction and clingingcharacteristics at these transition points of the incoming or outgoingfiber mats. Therefore, the entire true weight does not react on theweighing apparatus.

A further factor influencing weight determination with known weighingapparatuses at transition points between the incoming and outgoing fibermats to and from the weighing belt is the uniformity of the materialwhich is found in this zone. If the material which is to be weighedbetween these transition points has the same density, then an effectiveweight reference necessary to match the actual length of the weighingbelt can be determined by a series of measurements. However, if thematerial is not uniform within the transition points, then the weightwhich is recorded as a ratio of the length of the laid down material onthe weighing belt to the reference length also changes. Placing acorrection on the inconsistence of uniformity in the case of knownweighing apparatuses is not possible since a constant feed drive controlfor the feed of material is only workable with uniform material.

The purpose of the present invention is to create a band or mattingweighing device which avoids the disadvantage of the formation ofbridging and the weighing errors caused by this formation.

SUMMARY OF THE INVENTION

Objects and advantages of the invention will be set forth in part in thefollowing description or may be obvious from the description, or may belearned through practice of the invention.

One exemplary embodiment of the present invention provides for aweighing device for the determination of weight of a fiber material. Theweighing device includes two weighing arms, each of which are pivotablysupported on one end. Each of the weighing arms are supported on anopposite end by a weighing element. The weighing arms are configured forsupporting and transporting the fiber material. The weighing elementprovides a signal for the determination of the weight of the fibermaterial.

The present invention also encompasses a weighing device used for thecontinuous determination of weight per unit area:of fiber material. Theweighing device is located downstream from a fiber working machine or afiber material container that transports the fiber material to theweighing device. Also, the weighing device is located upstream from afiber working machine or a fiber material storage apparatus to whichfiber material is transported from the weighing device. The weighingdevices includes two weighing arms that are both rotationally supportedon one end by an axle. A feed apparatus is present and is locatedproximate to the rotationally supported end of one of the weighingdevices. Also included is a removal apparatus that is located proximateto the rotationally supported end of another of the weighing arms. Aweighing element is present which supports the end of the weighing armsopposite from the end of the weighing arms that are rotationallysupported.

Another exemplary embodiment of the present invention exists in aprocess for the continuous determination of the surface weight of fibermaterial. The process includes the step of transporting the fibermaterial over two weighing arms which are supported by a weighingelement on the two ends of the weighing arms that are proximate to oneanother. The process also includes the step of determining the weightthat is lying on each of the weighing arms. Further, the processincludes the step of the determination of the surface weight by takingthe arithmetical average of the two measured values.

The present invention also encompasses the weighing device as discussedabove where each of the weighing arms has a separate weighing elementsupporting the ends of the weighing arms.

Additionally, the present invention also includes an exemplaryembodiment of a weighing device as discussed above which further has atransport belt located on the weighing arms. The transport belt acceptsthe fiber material from the feed apparatus and transports the fibermaterial to the removal apparatus.

Alternatively, the present invention includes an exemplary embodiment ofa weighing device as discussed above where each of the weighing arms hasa transport belt for transporting the fiber material and each of thetransport belts has a turn-around roll. The weighing arms are rotatableabout each respective turn-around roll.

Also provided according to the present invention is a weighing device asdiscussed above which further has a compensating balance on each of theweighing arms to counterbalance the weight of the weighing arms.

A further exemplary embodiment of the present invention exists in aweighing device as immediately discussed where the compensating balancehas a compensation weight. The compensation weight is located thereon inorder to compensate for the weight of the weighing arms.

Additionally, the present invention includes an exemplary embodiment ofa weighing device as previously discussed where the axle is a stationaryknife edge support.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details of the invention are explained with the aid of thedrawings. There is shown in:

FIG. 1 the weighing device in accord with an exemplary embodiment of theinvention connected to a feed hopper in a schematic presentation,

FIG. 2 the functional principle of the weighing device,

FIG. 3 the functional principle of the weighing device with compensationof the weight of the weighing arms, and

FIG. 4 the weighing device in accord with FIG. 3, arranged at thedischarge end of a hopper.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the invention,examples of which are shown in the drawings. Each example is provided byway of explanation of the invention, and not meant as a limitation ofthe invention. For example, features illustrated or described as part ofone embodiment may be used on another embodiment to yield still a thirdembodiment. These and other modifications and variations are within thescope and spirit of the present invention.

In accord with an exemplary embodiment of the present invention shown inFIG. 1, the weighing device is shown at the discharge end of a hopperfeeder 5. Here, the fiber material is conveyed over a feed table 51 toan ascending conveyor belt 52. An evener-roller 53 fulfills its functionin that the fiber material is forwarded in defined quantities and in asufficiently loose status through the discharge roll 54 of a feed shaft55. At the lower discharge opening of the feed shaft 55 a feed roll 56is placed. The feed roll 56 sends the fiber material over a feed plate57 in a compressed form to a weighing device 1. By this operation, theweight per unit area is controlled so that the removal roll 58 sends acontinually uniform quantity of fiber material to the take-away roll 59.Thereafter, the material is discharged onto the transport belt 6. Thistransport belt 6 conducts the fiber material to a further fiber workingprocess.

FIG. 2 schematically presents the principle of the weighing device 1. Aweighing arm 2 is placed in transport connection with the feed roll 56and the feed pan 57, but is physically separate from both. The weighingarm 2 is supported on a stationary knife edge 21. The other end of theweighing arm 2 supports itself on a weighing element 3. The weighing arm2 is connected by a linked support 31 with the weighing element 3. Inmirror image to the disposition of weighing arm 2, another weighing arm2′ is placed. Weighing arm 2′ supports itself likewise on a weighingelement 3′ by means of a linked support 31′. On its other end, weighingarm 2′ is likewise supported by a stationary knife edge 21′. At thissupported end of the weighing arm 2′ a removal roll 58 is present whichin conjunction with a take-away roll 59 ejects the fiber material onto atransport belt 6 for further working. As is shown in FIG. 4, instead ofa removal roll 58 and a take-away roll 59, it is also possible to have aremoval roll-pair 58 and 58′ incorporated.

FIG. 3 depicts another exemplary embodiment of the weighing device 1.Here, the weighing device is provided with a compensatory apparatus tobalance the weight of the weighing arm 2, 2′. This apparatus is abalance beam 32 which pivots on a stationary knife edge 34 leaving somebeam length to react against a counter knife edge 35 on the weighing arm2. Balancing of the weight of the weighing arm 2 is carried out by thecompensation weight 33. This compensation weight 33 is adjustable on thebalance beam 32, or made to match the compensating weight of theweighing arm 2 by means known in the art. Because of this compensation,the weighing element 3 need assume only the true fiber material weightand can be made essentially more sensitive than if the complete weighingarm 2 with its own weight additionally burdened the weighing element 3.

Fundamentally, the weighing arm 2 can be designed as a slide surface forthe fiber material, however it is more advantageous as shown in FIG. 1or FIG. 4 to provide thereon a transport belt 22. The transport belt 22loops over the turn-around roller 23 and is driven by this roller 23. Inthis manner, the fiber material obtains transport movement by means ofthe transport belt 22 so that no horizontal forces can enter undercertain circumstances to effect the weighing. Horizontal forces mayoccur under certain circumstances in a design based on a slidingsurface. One end of the weighing arm 20 can be rotationally supported bythe axle of the turn-around roll 23 (see FIG. 1) or alternately besupported on a stationary knife edge 21. The feed roll 56 is locatedabove this stationary knife edge 21 and serves to convey the fibermaterial out of the hopper 55 onto the transport belt 22. Inclusion ofthe axle of the turn-around roll 23, or alternately the knife edge 21,provides for a stationary support of the weighing arm 20. This preventsthe pressure of the fiber compacting feed roll 56 from acting upon theweighing device. This positioning of the weighing arm 20 causes theinevitable bridge formation to not effect the weighing result.

From the transport belt 22, the fiber material is then transferred tothe second transport belt 22′ of the weighing device 1 and conducted tothe removal roll 58, or the removal roll-pair 58, 58′. The formation ofbridging cannot be avoided either at the fiber transfer from thetransport belt 22 to the transport belt 22′, nor at the removal roll 58or the removal roll-pair 58, 58′. However, exactly as in the case of thefeed roll 56, because of the stationary support of the weighing arm 20′the material removal has no effect on the measurement result. At thesame time, upon the transition from the transport belt 22 to thetransport belt 22′, the weighing elements (3, 3′) now weigh thebridging. This is because the fiber material mat of the belt 22 is onlysupported on the weight-sensitive zone of the other transport belt 22′so that the average of the two measured values present the true valuewithout bias from the bridge build up. In accord with the respectivedetermined weight, the regulation of the material transport speed in thearea of the material feed is then carried out in a conventional manner.

It should be understood that the invention includes variousmodifications that can be made to the embodiments of the weighing devicedescribed herein as come within the scope of the appended claims andtheir equivalents.

What is claimed is:
 1. A weighing device for determination of weight ofa fiber material comprising: at least two weighing arms, each of saidweighing arms being stationarily pivotably supported on one end at astationarily fixed pivot point, and each of said weighing arms beingsupported on an opposite end by a separate respective weighing element,said weighing arms configured for supporting and transporting the fibermaterial, each respective said weighing element providing a signal forthe determination of weight of the fiber material.
 2. The weighingdevice of claim 1, further comprising: a feed apparatus proximate tosaid pivotably supported end of one of said weighing arms, said feedapparatus used for the transporting of the fiber material; and a removalapparatus on said pivotably supported end of the other of said weighingarms, said removal apparatus transporting the fiber material from saidweighing device.
 3. The weighing device of claim 1, wherein saidweighing arms are linkably engaged with said weighing element.
 4. Theweighing device of claim 2, further comprising a transport belt locatedon said weighing arms, said transport belt accepts the fiber materialfrom said feed apparatus and transports the fiber material to saidremoval apparatus.
 5. The weighing device of claim 1, wherein each ofsaid weighing arms has a transport belt for transporting the fibermaterial, said transport belts each have a turn-around roll, and saidweighing arms are rotatable about each respective said turn-around roll.6. The weighing device of claim 1, further comprising a compensatingbalance on each of said weighing arms to counterbalance the weight ofsaid weighing arms.
 7. The weighing device of claim 6, wherein saidcompensating balance has a compensation weight located thereon in orderto compensate for the weight of said weighing arms.
 8. A weighing devicefor continuous determination of weight per unit area of fiber material,said weighing device being located downstream from a fiber workingmachine or a fiber material container that transports the fiber materialto said weighing device, and said weighing device located upstream froma fiber working machine or a fiber material storage apparatus to whichfiber material is transported from said weighing device, comprising: atleast two weighing arms, each of said weighing arms being rotationallysupported on one end by an axle, said axle being stationarily fixed soas not to move in a vertical direction; a feed apparatus locatedproximate to said rotationally supported end of one of said weighingdevices; a removal apparatus being located proximate to saidrotationally supported end of another of said weighing arms; and aseparate respective weighing element supporting the end of said weighingarms opposite from the end of said weighing arms that are rotationallysupported, wherein a signal from each of said weighing elements is usedto compute a total weight of the fiber material transported over saidweighing arms.
 9. The weighing device of claim 8, wherein said weighingarms linkably engage said weighing element.
 10. The weighing device ofclaim 8, further comprising a transport belt located on each of saidweighing arms, said transport belt accepts the fiber material from saidfeed apparatus, and said transport belt transports the feed material tosaid removal apparatus.
 11. The weighing device of claim 10, whereineach of said transport belts has a turn-around roll on each of saidweighing arms, and said weighing arms are rotatable about the axis ofsaid respective turn-around roll.
 12. The weighing device of claim 8,wherein each of said weighing arms has compensating balance tocounterbalance the weight of said weighing arms.
 13. The weighing deviceof claim 12, wherein each of said compensating balance has acompensation weight to compensate for the weight of said weighing arms.14. The weighing device of claim 8, wherein each said axle is supportedon a stationary knife edge support.